HCl and ClO profiles inside the Antarctic vortex as observed by SMILES in November 2009: comparisons with MLS and ACE-FTS instruments

摘要

We present vertical profiles of hydrogen chloride (HCl) and chlorine monoxide(ClO) as observed by the Superconducting Submillimeter-Wave Limb-EmissionSounder (SMILES) on the International Space Station (ISS)inside the Antarctic vortex on 19–24 November 2009. The SMILES HCl valuereveals 2.8–3.1 ppbv between 450 K and 500 K levels in potential temperature(PT). The high value of HCl is highlighted since it is suggested that HClis a main component of the total inorganic chlorine (Cl_y),defined as Cl_y ? HCl + ClO + chlorine nitrate (ClONO₂), inside theAntarctic vortex in spring, owing to low ozone values. To confirm the qualityof two SMILES level 2 (L2) data products provided by the Japan AerospaceExploration Agency (JAXA) and Japan's National Institute of Information andCommunications Technology (NICT), vis-à-vis the partitioning ofCl_y, comparisons are made using other satellite data from the Aura MicrowaveLimb Sounder (MLS) and Atmospheric Chemistry Experiment Fourier TransformSpectrometer (ACE-FTS). HCl values from the SMILES NICT L2 product agree towithin 10% (0.3 ppbv) with the MLS HCl data between450 and 575 K levels in PT and with the ACE-FTS HCl databetween 425 and 575 K. The SMILES JAXA L2 product is 10 to 20%(0.2–0.5 ppbv) lower than that from MLS between 400 and700 K and from ACE-FTS between 500 and 700 K. For ClO in daytime, thedifference between SMILES (JAXA and NICT) and MLS is lessthan ±0.05 ppbv (100 %) between 500 K and 650 K withthe ClO values less than 0.2 ppbv. ClONO₂ values as measured by ACE-FTSalso reveal 0.2 ppbv at 475–500 K level, resulting in the HCl / Cl_y ratios of0.91–0.95. The HCl / Cl_y ratios derived from each retrievalagree to within ?5 to 8 % with regard to their averages. The high HCl valuesand HCl / Cl_y ratios observed by the three instruments in the lowerstratospheric Antarctic vortex are consistent with previous observations inlate Austral spring.